#define _CRT_SECURE_NO_WARNINGS 
#include <stdio.h>

int main() {
    double h;
    double sum = 0;
    for (int i = 0; i < 5; i++)
    {
        scanf("%lf", &h);
        sum += h;
    }
    printf("%.2lf", sum / 5);
    return 0;
}